1. Field of the Invention
This invention relates to disk drive systems, and relates more particularly to such disk drive systems having a low height or profile, improved serviceability, reliability and removability without sacrificing capacity or performance.
2. Prior Art
Over the past ten years, disk drive devices for use in computer systems have been dramatically shrinking in size. One of the factors responsible for this rapid progress has been the ability to reduce the space required to house the electronic components of the devices, made possible principally through very large scale integration of the electronic circuitry. Additionally, substantial advances have been made in reducing the size of the major mechanical components of disk drive devices such as the motor which rotates the disk or disks, the flexure mounting mechanism for the read/write heads and the actuator mechanism which moves the heads to different track positions on the disk surfaces.
With the increasing popularity of portable, laptop, notebook and smaller desktop personal computers employing disk drives, the pressure to reduce the volume of the disk drive enclosure without sacrificing the capacity, performance and cost of the storage device is significant. A hard disk drive manufacturer must supply a product having a very high linear bit density and radial track density in a device that is resistant to shock and vibration, is temperature and environment tolerant, is producible in high volume at a reasonable cost, has high throughput performance, and has a storage capacity that meets the increasing data storage requirements of the computer system market. In most small computer systems, the size of the keyboard and the visual display or monitor will dictate the mandatory X and Y dimensions for the system. This means that the most critical disk drive dimension that can be controlled is the height or Z dimension of the drive.
The relatively recent introduction of 2.5 inch and 1.8 inch xe2x80x9cform factorxe2x80x9d disk drives has been a response to this demand for high capacity, low volume storage for the smaller types of computers. Representative examples of prior art disk drive designs directed to the 2.5 inch and 1.8 inch form factor drives are the following.
U.S. Pat. No. 5,025,335, Stefansky, shows a disk drive employing a 2.5 inch disk in a housing whose length is described as equal to the width of a conventional 3.5 inch disk drive (4 inches) and whose width is approximately one half the length of a 3.5 inch drive (2.75 inches). In an embodiment with one disk in the housing, the height of the unit is 0.68 inches, with a printed circuit board containing the drive electronics mounted adjacent to and outside the bottom of the housing.
U.S. Pat. No. 5,025,336, Morehouse et al, discloses a reduced height disk drive with a single 2.5 inch disk therein, the drive housing having a width of approximately 2.8 inches, a length of approximately 4.0 inches and an overall height no greater than 0.63 inches. The patent attributes this reduced height to the use in the disk enclosure of disk spin motors, actuators and head flexures of smaller height. This drive utilizes a printed circuit board with the drive electronics therein disposed below the base which supports the disk and actuator and outside the disk enclosure.
U.S. Pat. No. 4,933,785, Morehouse et al, shows a drive containing at least two 2.5 inch disks therein, with the printed circuit board containing the device electronics mounted below and spaced from the disk enclosure.
U.S. Pat. No. 5,038,239, Vettel et al., discloses a disk drive in which the electronic circuits are disposed mounted on a number of circuit cards which are mounted in different areas in the drive housing, with interconnections between the multiplicity of cards.
The present invention provides a very low height disk drive by locating the circuit board or boards containing the drive electronics in the same enclosure which contains the head-disk assembly (HDA). The structure of this invention includes a first volume and a second volume, the first volume being a sealed volume containing at least one rigid disk, and the second volume being a circuit volume separate from the sealed volume and containing electronics for controlling the disk drive system. In the case of a drive having a single disk therein, the electronic circuitry board is disposed in substantially the same plane as the plane of the single disk. In the case of multiple disks in a drive enclosure, the electronic circuitry board is disposed in a plane between the planes of the surfaces of two of the disks. This low profile is made possible, in part, by locating the drive actuator mechanism near the side and at one end of the drive enclosure, thereby leaving space in the enclosure to mount the circuit board in the space adjacent to the actuator.
In the prior art disk drives discussed above, the printed circuit board or boards are placed above or below, or both above and below, the disk or disks, outside the drive enclosure. This results in problems with electrostatic charges which may be placed on the electronic components as a result of human hands touching the components when inserting or removing the disk drive assembly from its mounting in the using computer.
In the present invention, placement of all of the electronic components inside the small sealed enclosure totally protects the electronic components from damage from human handling. This design configuration results in a cartridge-like device with a compact, smooth rectangular configuration, making it very suitable for use as a removable type device, without any modification. At the same time, this invention provides for mounting of the printed circuit board or boards in the enclosure in a manner which permits its or their removal therefrom for replacement or repair without the need to remove the entire disk drive assembly from the computer.
Additionally, by mounting the flexible cables associated with the circuit board totally within the enclosure, the circuits in these cables are shielded from external electromagnetic interference (EMI). Further, the HDA is placed in a separate sealed compartment inside the enclosure to prevent contaminants from reaching the disk surfaces and causing head crashes.
The disk storage device of this invention can be used in workstations, desktop and portable computers, notebooks and peripheral devices such as facsimile machines, laser printers, oscilloscopes, instruments, etc., where minimumn dimensional volume is critical, but where no degradation of capacity, performance and/or cost is allowed.
The present invention provides an extremely thin disk drive, with a 0.350-inch high profile for a single disk enclosure, a 0.500-inch high profile for a two disk enclosure, 0.750-inch high profile for a four disk configuration and a 1.00 inch high profile for a six disk configuration. In representative configurations utilizing 3.5 inch disks, the disk drive system of this invention may have a width of approximately 4 inches and a length of approximately 5.75 inches regardless of the number of disks utilized in the enclosure. An embodiment of this invention having two 3.5 inch disks therein weighs approximately 10 ounces, while a similar version utilizing magnesium parts for the housing weighs approximately 8 ounces.
When 3.5 inch disks are employed in the invention, a formatted capacity of 240 megabytes (MB) is obtained with two disk embodiment, a formatted capacity of 120 MB is obtained with a one disk embodiment, and a formatted capacity of 480 MB results from a four disk configuration. If 2.5 inch or 1.8 inch diameter disks are employed using the configuration of the present invention, comparable low profiles can be obtained.